The potential of hydrogen electrode is −118.5 mV. The H+ concentration of the solution is:
Given:
E=−118.5 mV=118.5×10−3 V
We know that,
Ecell=0.0591nlog[H+]
Here,
n=1
So,
log[H+]=−118.5×10−30.0591
log[H+]=−2.0051
[H+]=0.01 M
Hence, this is the required answer.